Bump laravel-mix from 4.0.12 to 4.0.13 (#222)

Bumps [laravel-mix](https://github.com/JeffreyWay/laravel-mix) from 4.0.12 to 4.0.13.
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<summary>Commits</summary>

- [`41d5d56`](laravel-mix/laravel-mix@41d5d56) 4.0.13
- [`624677b`](laravel-mix/laravel-mix@624677b) Fix Log tests
- [`4ab25a7`](laravel-mix/laravel-mix@4ab25a7) Switch to feedback
- [`2ef2118`](laravel-mix/laravel-mix@2ef2118) Remove extra line break
- [`26e12f0`](laravel-mix/laravel-mix@26e12f0) Indent feedback
- [`d29d208`](laravel-mix/laravel-mix@d29d208) Check for the Yarn program, not yarn.lcok
- [`e44eb44`](laravel-mix/laravel-mix@e44eb44) fix typo in CopyFilesTask for Log.feedback ([#1898](https://github-redirect.dependabot.com/JeffreyWay/laravel-mix/issues/1898))
- [`b6f7ff9`](laravel-mix/laravel-mix@b6f7ff9) Change Mix's default OS system notification timeout to 2 seconds, 5 seconds i...
- [`701bdb5`](laravel-mix/laravel-mix@701bdb5) Fixed incorrect JSDoc parameter ([#1895](https://github-redirect.dependabot.com/JeffreyWay/laravel-mix/issues/1895))
- [`9acd472`](laravel-mix/laravel-mix@9acd472) Extract Log class
- Additional commits viewable in [compare view](laravel-mix/laravel-mix@v4.0.12...v4.0.13)
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